GM Corsica/Beretta 1988-1996 Repair Guide

Alternator

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The alternating current generator (alternator) supplies a continuous output of electrical energy at all engine speeds. The alternator generates electrical energy for the engine and all electrical components, and recharges the battery by supplying it with current. This unit consists of four main assemblies: two end frame assemblies, a rotor assembly, and a stator assembly. The rotor is supported in the drive end frame by a ball bearing and at the other end by a roller bearing. These bearings are lubricated during manufacture and require no maintenance. There are six diodes in the end frame assembly. Diodes are electrical check valves that change the alternating current supplied from the stator windings to a direct current (DC), delivered to the output (BAT) terminal. Three diodes are negative and are mounted flush with the end frame; the other three are positive and are mounted into a strip called a heat sink. The positive diodes are easily identified as the ones within small cavities or depressions. A capacitor, or condenser, mounted on the end frame protects the rectifier bridge and diode trio from high voltages, and suppresses radio noise. This capacitor requires no maintenance.

Two sizes of the CS series alternator are used on the Corsica/Beretta cars, the CS-121 and CS-130, denoting the OD in mm of the stator laminations.

The alternator is serviced as a complete assembly.

CHARGING SYSTEM TROUBLESHOOTING



There are many possible ways in which the charging system can malfunction. Often the source of a problem is difficult to diagnose, requiring special equipment and a good deal of experience. This is usually not the case, however, where the charging system fails completely and causes the dash board warning light to come on or the battery to become dead. To troubleshoot a complete system failure only two pieces of equipment are needed: a test light, to determine that current is reaching a certain point; and a current indicator (voltmeter), to determine the direction of the current flow and its measurement in Volts.

This test works under three assumptions:

  1. The battery is known to be good and fully charged.
  2.  
  3. The alternator belt is in good condition and adjusted to the proper tension.
  4.  
  5. All connections in the system are clean and tight.
  6.  

In order for the current indicator to give a valid reading, the car must be equipped with battery cables which are of the same gauge size and quality as original equipment battery cables.

  1. For vehicles without charge indicator lamp, go to step 7.
  2.  
  3. With the switch ON , engine stopped, the lamp should be on. If not, detach the harness at the alternator and ground the L terminal.

    If the lamp lights, replace or repair the alternator.
     
    If the lamp does not light, locate the open circuit between the grounding lead and the ignition switch. Lamp may be open.
     

  4.  
  5. With the switch on and the engine running at moderate speed, the lamp should be off. If not, detach the wiring harness at the alternator.

    If the lamp goes off, replace or repair the alternator.
     
    If the lamp stays on, check for a grounded L terminal in the wiring harness.
     

  6.  
  7. Battery undercharged or overcharged.

    Detach the wiring harness connector from the alternator.
     
    With the switch on, engine not running, connect the voltmeter from ground to the L terminal.
     
    A zero reading indicates an open circuit between the terminal and the battery. Correct as required.
     
    Reconnect the harness connector to the alternator and run the engine at moderate speed.
     
    Measure the voltage across the battery. If above56V, replace or repair alternator
     

  8.  
  9. Turn on the accessories, load the battery with a carbon pile (variable rheostat that controls the flow of electric current) to obtain maximum amperage. Maintain voltage at53V or below.

    If within55 amperes of rated output, the alternator is OK.
     
    If not within55 amperes of rated output, replace or repair alternator.
     

  10.  

REMOVAL & INSTALLATION



2.0 and 2.2L Engines

See Figure 1

  1. Disconnect the negative battery cable.
  2.  


CAUTION
Failure to disconnect the negative cable may result in injury from the positive battery lead at the alternator, and may short the alternator and regulator during the removal process.

  1. Remove the serpentine drive belt from the alternator.
  2.  
  3. For5990-92 vehicles remove the 3 bolts from the alternator brace (including bolt from the alternator to the brace).
  4.  
  5. For5993-96 vehicles, remove the 2 bolts from the alternator brace (including bolt from the alternator to the brace).
  6.  
  7. For5988-90 vehicles, remove the two alternator mounting bolts.
  8.  
  9. For5991-96 vehicles, perform the following:
    1. Remove the upper bracket nut from the exhaust manifold.
    2.  
    3. Remove the upper bracket bolt.
    4.  
    5. Remove the upper bracket with the heat shield.
    6.  

  10.  
  11. Detach the alternator electrical connections.
  12.  
  13. Remove the alternator from the vehicle.
  14.  

To install:
  1. Position the alternator in the vehicle and attach the electrical connections. Tighten the battery lead nut to 65 inch lbs. (7.5 Nm).
  2.  
  3. For5988-90 vehicles, install the two alternator mounting bolts.
  4.  
  5. For5991-96 vehicles, perform the following:
    1. Install the upper bracket with the heat shield.
    2.  
    3. Install the upper bracket bolt and nut(s).
    4.  

  6.  
  7. Install the 2 or 3 alternator mounting bolts, as applicable.
  8.  
  9. Tighten the rear alternator bolt to 22 ft. lbs. (30 Nm).
  10.  
  11. For5988-92 vehicles, tighten the upper bracket bolt and bracket nut to 22 ft. lbs. (30 Nm).
  12.  
  13. For5993-96 vehicles, tighten the bracket nuts to 32 ft. lbs. (8 Nm).
  14.  
  15. Tighten the 2 upper alternator mounting bolts to 22 ft. lbs. (30 Nm).
  16.  
  17. Tighten the lower alternator mounting bolt and nut to 33-37 ft. lbs. (14-50 Nm).
  18.  
  19. Install the serpentine drive belt.
  20.  
  21. Connect the negative battery cable.
  22.  



Click image to see an enlarged view

Fig. Fig.1: Exploded view of the alternator and mounting brackets - 2.0L and 2.2L (VIN G) engines

2.3L Engine

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the serpentine drive belt.
  4.  


CAUTION
When rotating the serpentine belt tensioner, be sure to use tool J 37059 or a tight fitting53mm wrench at least 24 in. (610mm) long to avoid personal injury.

  1. Remove the coolant and washer reservoir attaching screws.
  2.  
  3. Detach the washer fluid pump electrical connector, then and position the reservoir aside.
  4.  
  5. If equipped, remove the A/C line rail clip.
  6.  
  7. If equipped, disconnect the 2 vacuum lines at the front of the engine and remove vacuum harness attaching bracket.
  8.  
  9. Remove the alternator mounting bolts.
  10.  
  11. Reposition the alternator to access the wiring, then tag and detach the alternator electrical connections and battery lead.
  12.  
  13. Position the harness out of the way.
  14.  
  15. Carefully remove the alternator from between the mounting bracket and the A/C compressor and condenser hoses.
  16.  

Be very careful when removing or installing the alternator as not to damage the air conditioner compressor and/or condenser hoses.

Click image to see an enlarged view

Fig. Fig. 2: 2.3L engine alternator mounting - front view shown

To install:
  1. Place the alternator in the vehicle, between the air conditioner compressor and condenser hoses.
  2.  
  3. Position the alternator in order to connect the wiring. Attach the electrical connector and battery lead. Tighten the battery lead to 65 inch lbs. (7.5 Nm).
  4.  
  5. Install the alternator mounting bolts.
  6.  
  7. Tighten the rear mounting bolts to 20 ft. lbs. (26 Nm) and the front mounting bolt to 37-2 ft. lbs. (50-54 Nm).
  8.  
  9. For5990-91 vehicles, tighten the upper front mounting bolt to59 ft. lbs. (26 Nm).
  10.  
  11. If removed, install the vacuum harness attaching bracket and connect the vacuum lines at the front of the engine.
  12.  
  13. If equipped, install the A/C line rail clip.
  14.  
  15. Attach the washer pump electrical connector.
  16.  
  17. Position the coolant/washer pump reservoir and secure with the retaining screws.
  18.  
  19. Install the serpentine drive belt.
  20.  


CAUTION
To avoid personal injury when rotating the serpentine belt tensioner, be sure to use a tight fitting53mm wrench at least 24 in. (610mm) long.

  1. Connect the negative battery cable.
  2.  
  3. Start the engine and perform a charging system test.
  4.  

2.8L and 3.1L Engines

See Figures 3, 4, 5, 6, 7, 8, 9, 10 and 11

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the serpentine drive belt.
  4.  
  5. If accessible at this time, detach the alternator electrical connector.
  6.  
  7. Remove the three alternator mounting bolts.
  8.  
  9. For5995-96 vehicles, detach the alternator air intake connector.
  10.  
  11. Label and detach the remaining electrical connector(s) from the back of the alternator.
  12.  
  13. Remove the alternator from the vehicle.
  14.  

To install:
  1. Position the alternator in the vehicle.
  2.  
  3. Attach the alternator electrical connectors. Tighten the battery lead nut to 65 inch lbs. (7.5 Nm).
  4.  
  5. For5995-96 vehicles, attach the alternator air intake connector.
  6.  
  7. Install the alternator-to-mounting bracket bolts and tighten as follows:
    1. Tighten the rear stud and bolt to58 ft. lbs. (25 Nm).
    2.  
    3. Tighten the front bolt to58 ft. lbs. (25 Nm).
    4.  
    5. Tighten the rear bolt to support to 37 ft. lbs. (50 Nm).
    6.  

  8.  
  9. Install the serpentine drive belt.
  10.  
  11. Connect the negative battery cable.
  12.  
  13. Start the engine and perform a charging system test.
  14.  



Click image to see an enlarged view

Fig. Fig. 3: Front view of the alternator attachment - 3.1L (VIN M) engine



Click image to see an enlarged view

Fig. Fig. 4: Remove the serpentine drive belt from the alternator



Click image to see an enlarged view

Fig. Fig. 5: Unplug the alternator electrical connector



Click image to see an enlarged view

Fig. Fig. 6: Remove the alternator mounting bolts



Click image to see an enlarged view

Fig. Fig. 7: On5995-96 vehicles, you must detach the alternator air intake connector



Click image to see an enlarged view

Fig. Fig. 8: To remove the air intake connector, use a suitable tool (see arrow) to unfasten the retainers ...



Click image to see an enlarged view

Fig. Fig. 9: ... then pull the air intake connector from the back of the alternator



Click image to see an enlarged view

Fig. Fig. 10: Unfasten the retaining nut securing the BAT cable to the alternator ...



Click image to see an enlarged view

Fig. Fig. 11: ... then detach the remaining connector(s) and remove the alternator from the vehicle

 
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